Content for This Unit

Video

The study of gravity has played a central role in the history of science—from Galileo and Newton to Einstein's twentieth century theory of general relativity. Yet, in spite of five centuries of study, many aspects of gravity remain a mystery. How can gravity, which in many ways is the dominant force in the universe, be at the same time, by far, the weakest of the four known forces in nature? See how physicists are approaching this question through two topics of intense research in gravitational physics today: short-scale measurements of gravity's inverse-square law, and the search for ripples in space-time known as gravitational waves.